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Hi all

I'm currently riding a Spesh Tricross that has a BB-7420 bottom bracket with crank bolts but it's nearing the end of it's life!
It's been suggested to me that it's a pretty pants bottom bracket anyway so wondered if any of you could recommend a better replacement please?
It's also got an FSA Temp triple crankset fitted but I'm happy to listen to suggestions for replacing that too!

Thanks  3

6 comments

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Derny [113 posts] 2 years ago
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The BB-7420 came in different spindle lengths. The length should be printed on it, but it's probably only visible if you remove it from the bike.

You should get a bottom bracket of the exact same dimensions as the one you are removing, and you should have quite a few choices ranging from cheap to high quality.

If you are considering replacing the crankset then you should definitely make that decision before replacing the bottom bracket, since any investment in the bottom bracket will be wasted if you replace the crankset.

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bikebot [2149 posts] 2 years ago
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That's an easy one, well it is for me having done exactly that replacement this spring. That FSA part is a little notorious for conking out early, so I swapped my own after riding it through the Winter rather than wait for it to happen.

Buy yourself a Shimano UN55, cheap (under £15 online), reliable and very easy to find.

For Specialized, you'll probably be able to find size details for the BB online somewhere, otherwise as Derny says, pull the old one out. If you can't get the exact width, you have a little wiggle room. I had to replace a 103mm with a 107mm as that's the smallest size for the UN55, but still within reach of the front mech after adjustment.

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Dangermouse [13 posts] 2 years ago
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bikebot wrote:

That's an easy one, well it is for me having done exactly that replacement this spring. That FSA part is a little notorious for conking out early, so I swapped my own after riding it through the Winter rather than wait for it to happen.

Buy yourself a Shimano UN55, cheap (under £15 online), reliable and very easy to find.

For Specialized, you'll probably be able to find size details for the BB online somewhere, otherwise as Derny says, pull the old one out. If you can't get the exact width, you have a little wiggle room. I had to replace a 103mm with a 107mm as that's the smallest size for the UN55, but still within reach of the front mech after adjustment.

Thanks - the UN55 is a good price! Did you change your crankset too?

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bikebot [2149 posts] 2 years ago
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Dangermouse wrote:

Thanks - the UN55 is a good price! Did you change your crankset too?

No, a lot of people advise that for taper mount, but I take it with the same pinch of salt as the advice that you change your cassette with your chain. If you dare to raise the question of whether to grease or not to grease the taper assembly, you'll find a wide range of opinions!

Clean everything up before putting the old chainset back on and use a torque wrench (reversible for the BB) unless you've got a good feel for that much force.

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kie7077 [887 posts] 6 months ago
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bikebot wrote:

That's an easy one, well it is for me having done exactly that replacement this spring. That FSA part is a little notorious for conking out early, so I swapped my own after riding it through the Winter rather than wait for it to happen. Buy yourself a Shimano UN55, cheap (under £15 online), reliable and very easy to find. For Specialized, you'll probably be able to find size details for the BB online somewhere, otherwise as Derny says, pull the old one out. If you can't get the exact width, you have a little wiggle room. I had to replace a 103mm with a 107mm as that's the smallest size for the UN55, but still within reach of the front mech after adjustment.

 

Nice one, just googled bb 7420 and your post came up, thanks for the pointer. My FSA bracket did last many thousands of miles though, getting a bit grindy now.

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Jack Osbourne snr [570 posts] 6 months ago
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FSA - Fucking Shite Always

They use the crappiest seals and bearings known to man...even in their higher end offerings. It's a shame, because a lot of their stuff is good...just not the stuff with bearings.